JP2836283B2 - Buffer management method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buffer management system in a multiprocessor system in which a plurality of central control units transfer data to the same buffer.

[0002]

2. Description of the Related Art Conventionally, an auto-increment pointer method is known as a buffer management method in a multiprocessor system in which a plurality of central control units transfer data to the same buffer. In this auto-increment pointer method, before each central control unit transfers data to a buffer, the value of a pointer existing at a specific address is read, and the start position of a buffer area to be accessed is determined. The value is incremented by "1" each time it is read, and indicates the head position of the buffer area to be accessed next. By employing such an auto-increment pointer method, it is possible to prevent data transferred from each central control unit from being written into the same buffer area.

[0003]

SUMMARY OF THE INVENTION The above-mentioned conventional method is as follows.
The updated value of the pointer is fixed at "1". That is, 1
Since the length of the buffer area that can be used in one data transfer is fixed, if the buffer area is too short, data longer than the length of the buffer area must be transferred in several batches, which reduces the transfer speed. . On the other hand, if the length of the buffer area is increased, even a very short data will wastefully occupy the buffer.

[0004] It is an object of the present invention to provide a buffer management system capable of improving data transfer speed and buffer utilization efficiency.

[0005]

According to the present invention, to achieve the above object, a plurality of central control units output the address of a pointer, read the value of the pointer, and transfer data to a buffer according to the read pointer value. When transferring data to the buffer, the central control unit reads the value of the pointer by outputting the address of the pointer to which information on the data length of the transfer data has been added. Transferring the data to which the header is added according to the value of the read pointer to the buffer, and updating the value of the pointer according to the information on the data length by reading the value of the pointer by the central control unit; An apparatus for processing stored data has an internal pointer to the buffer, When accessing the buffer, it is determined whether or not a header exists at a position on the buffer having a predetermined relationship with the value of the internal pointer, and if it is determined that the header exists, the buffer is stored in accordance with the value of the internal pointer. After the access, the value of the internal pointer is updated according to the data length, and when it is determined that the internal pointer does not exist, the buffer is searched for a header, and the value of the internal pointer is corrected according to the searched position.

[0006]

[0007]

In the present invention, each central control unit reads the contents of the pointer before transferring data to the buffer. At this time, the central control unit outputs, as a read address, a value obtained by adding information on the data length of the transfer data to the address of the pointer. Then, when reading the value of the pointer, the central control unit transfers the data with the header added to the buffer according to the value of the read pointer.

[0008]

When the value of the pointer is read out by the central control unit, the value is updated according to the information on the data length.

When accessing the buffer, the apparatus for processing the data stored in the buffer determines whether or not a header exists at a position on the buffer having a predetermined relationship with the value of the internal pointer. . Then, if it is determined that the buffer exists, the buffer is accessed according to the value of the internal pointer, and then the value of the internal pointer is updated according to the data length. When it is determined that the header does not exist, the buffer is searched for the header, and the value of the internal pointer is corrected according to the searched position.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, in which central control units (CP) 1-4, a system bus 5,
It comprises an I / O panel 6, a bus arbitration circuit 11, and a line 12.

The I / O panel 6 includes a two-port RAM 7. A buffer (transmission,
A reception buffer 8, an external pointer 9, and an internal pointer 10 are configured.

When the two-port RAM 7 is viewed from the inside of the I / O panel 6, as shown in FIG. 2, addresses $ 8000 to $ FFFF are assigned as simple RAMs, and reading and writing can be performed freely.

When viewed from the system bus 5 side, addresses $ 0000 to $ 7FFF are allocated and divided into the following three areas.

Buffer area 8E Corresponds to the buffer 8 and is an area where the central control units 1 to 4 can freely read and write.

External pointer area 9E This area corresponds to the external pointer 9 and can be freely read and written by the central control units 1 to 4. Information indicating the position on the buffer 8 to be accessed next by the central control units 1 to 4 is stored in the external pointer area 9E, and the value is read out by hardware immediately after the value is read out by the central control units 1 to 4. Changed automatically.

Internal pointer area 10E Corresponds to the internal pointer 10, and is an area dedicated to the I / O panel 6 that cannot be read or written by the central control units 1 to 4. The internal pointer area 10E stores information indicating the position on the buffer 8 to be accessed next by the I / O panel 6.

FIGS. 3 and 4 are flowcharts showing processing examples of the central control units 1-4 and the I / O panel 6. The operation of this embodiment will be described below.

Each of the central controllers 1 to 4 outputs a bus use request to the bus arbitration circuit 11 when transferring data to the buffer 8, and when a bus use permission is given from the bus arbitration circuit 11, the processing shown in FIG. To start.

First, the central control unit (to be referred to as the central control unit 1) to which the bus use permission is given obtains the block length Li of the transfer block including the data to be transferred (step S3).
1) and then the external pointer 9 based on the block length Li
Is obtained (step S32). now,
For example, assuming that the minimum management unit of the external pointer 9 for managing the buffer 8 is 64 bytes, the central control unit 1 divides the block length Li by “64”, and adds 1 to the integer part.
Is set as the update value Lb.

Next, the central control unit 1 outputs a value obtained by adding an updated value Lb to the lower side of the address of the external pointer 9 to the system bus 5 as a read address.
Is read out (Step S33).

When the value PTRe of the external pointer 9 is read by the central control unit 1, the I / O panel 6 uses the adding means 51 to add the value PTRe of the external pointer 9 as shown in FIG.
The updated value Lb is added to Re. The updated value PTRe of the external pointer 9 indicates the start position of the next data transfer to the buffer 8.

The central control unit 1 stores the value PTR of the external pointer 9
After reading e, the start address of the area on the buffer 8 for storing the transfer block is obtained based on the value PTRe (step S34). Next, the central control unit 1 adds the buffer busy flag B and the bed H to the data as shown in FIG.
A transfer block to which the EADER and the block length Li are added is created and transferred to the buffer 8 (step S3).
5). When the transfer of the transfer block is completed, the buffer busy flag B is set to "1" to indicate that the transfer has been completed (step S36), and the process ends.

Next, the processing of the I / O panel 6 will be described with reference to FIG.

When processing the data stored in the buffer 8, the I / O panel 6 first obtains the start position of the transfer block based on the value PTRI of the internal pointer 10.
(Step S41). Next, the I / O panel 6 determines whether or not the header HEADER exists at a position having a predetermined relationship with the head position of the transfer block (step S).
42). It is desirable that the value of the header HEADER be set to a unique value that does not overlap with other data as much as possible.

When it is determined that the header HEADER exists (when the value PTRI of the internal pointer 10 is a or b as shown in FIG. 7), the buffer busy flag B at the head position is set to "1". Is determined (step S43). When it is determined that the buffer busy flag B is not “1”, that is, when it is determined that the transfer of the transfer block has not been completed, the process waits until the buffer busy flag B becomes “1” and is “1”. If it is determined that the data has been read, the data is read from the above-mentioned head position on the buffer 8 and, for example, a process of transmitting the data to another device via the line 12 is performed (step S44).

Thereafter, the I / O panel 6 sets the buffer busy flag B to "0" to indicate that the processing is completed (step S45), and furthermore, the block length Li included in the processed transfer block. The value PTRI of the internal pointer 10 is updated on the basis of (Step S46), and the process returns to Step S41.

If it is determined in step S42 that the header does not exist at a predetermined position (an error occurs in the internal pointer 10 and the value PTRI is b 'as shown in FIG. (When it is on the way)
The I / O panel 6 searches the buffer 8 for a header (step S47), corrects the value PTRI of the internal pointer 10 based on the position of the found header (step S48), and then performs the process of step S41. Return to

[0030]

As described above, according to the present invention, the updated value of the pointer is changed based on the data length of the data transferred from each central control unit to the buffer. In this case, no buffer is used, and even if the data length is long, it is not necessary to perform the data transfer many times, so that the transfer processing can be speeded up.

Further, according to the present invention, since a header is added to the data transferred from the central control unit to the buffer, the value of the internal pointer is shifted, and the value is stored in the buffer stored in the buffer. Even if it shows something on the way,
The value of the internal pointer can be modified based on the position of the header, and the data stored in the buffer can always be processed from the beginning.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a memory map of a two-port RAM.

FIG. 3 is a flowchart illustrating a processing example of a central control unit.

FIG. 4 is a flowchart illustrating a processing example of an I / O panel.

FIG. 5 is a diagram illustrating an update operation of an external pointer.

FIG. 6 is a diagram showing a format of data transferred by a central control unit.

FIG. 7 is a diagram illustrating a method of using a header.

[Explanation of symbols]

 1-4 Central control unit (CP) 5 System bus 6 I / O panel 7 2-port RAM 8 Buffer 9 External pointer 10 Internal pointer 11 Bus arbitration circuit 12 Line

Claims (1)

(57) [Claims] 1. A multiprocessor system in which a plurality of central control units output the address of a pointer to read the value of the pointer, and transfer data to a buffer in accordance with the read pointer value. When transferring data to the buffer, after reading the value of the pointer by outputting the address of the pointer to which information on the data length of the transfer data has been added, the data with the header added according to the value of the read pointer is written. When the value is read by the central control unit, the value of the pointer is updated according to the information on the data length, and the device that processes the data stored in the buffer is transferred to the buffer. An internal pointer, and when accessing the buffer, the internal pointer It is determined whether or not a header exists at a position on the buffer having a predetermined relationship with the value of, and when it is determined that the header exists, after accessing the buffer according to the value of the internal pointer,
Updating the value of the internal pointer according to the data length;
A buffer management method, wherein when it is determined that there is no buffer, the buffer is searched for a header, and the value of the internal pointer is corrected according to the searched position.